statement_attributes

Statement attributes

The @Delete, @Insert, @Query, @Select and @Update annotations allow you to control some aspects of the execution of the underlying statement, such as the consistency level, timeout, etc.

As a parameter

If the last parameter of any of those methods is a Function<BoundStatementBuilder, BoundStatementBuilder> (or UnaryOperator<BoundStatementBuilder>), the mapper will apply that function to the statement before executing it:

@Dao
public interface ProductDao {
  @Select
  Product findById(
      int productId, Function<BoundStatementBuilder, BoundStatementBuilder> setAttributes);
}

Function<BoundStatementBuilder, BoundStatementBuilder> statementFunction =
    builder -> builder.setConsistencyLevel(DefaultConsistencyLevel.ONE).setPageSize(500);

Product product = dao.findById(1, statementFunction);

Use this if you need to execute the same DAO methods with different configurations that can change dynamically.

If you reuse the same set of attributes often, you can store the function as a constant to reduce allocation costs.

As an annotation

Attributes can also be provided statically by annotating the method with @StatementAttributes:

@Dao
public interface ProductDao {
  @Select
  @StatementAttributes(consistencyLevel = "ONE", pageSize = 500)
  Product findById(int productId);
}

It's possible to have both the annotation and the function parameter; in that case, the annotation will be applied first, and the function second:

@Dao
public interface ProductDao {
  @Select
  @StatementAttributes(consistencyLevel = "ONE", pageSize = 500)
  Product findById(
      int productId, Function<BoundStatementBuilder, BoundStatementBuilder> setAttributes);
}

// Will use CL = QUORUM, page size = 500
Product product =
    dao.findById(1, builder -> builder.setConsistencyLevel(DefaultConsistencyLevel.QUORUM));